The invention relates to a device for superposing sheets of paper or the like, comprising longitudinal transport devices, by means of which the sheets of paper, which lie side-by-side in two parallel rows in a paper path, can be moved in direction of movement of the paper, which extends in direction of the rows, one after the other into an assembly station, comprising a lower vacuum conveyance unit arranged in the assembly station below the paper path and associated with the one row, by means of which lower vacuum conveyance unite two sheets of paper coming from different rows can be superposed in pairs, and comprising a discharge device, by means of which the sheets of paper, which are superposed in pairs, are discharged simultaneously from the assembly station, whereby the vacuum conveyance unit has a continuous conveyor belt provided with perforations, which conveyor belt is guided over two guide rollers supported in a carrier and over a vacuum chamber arranged therebetween, which vacuum chamber is open toward the upper operating strand of the conveyor belt, which operating strand borders the paper path.
The device of the invention is used to superpose sheets of paper, for example forms which exit a cutting machine via a 2-path operation. A similar purpose is served by a conventional device of the abovementioned type according to the DE 34 33 497 A1. The sheets of paper lying side-by-side in two rows are in this conventional device fed one after the other into the assembly station. A perforated, continuous conveyor belt, which extends transversely to the direction of movement of the paper and is guided over a vacuum chamber, is provided in the assembly station. With this conveyor belt it is possible to move a sheet of paper coming from the first row of sheets of paper transversely with respect to the direction of movement of the paper over the other sheet of paper originating in the second row of sheets of paper and already in the assembly station. During the transverse transport of the one sheet of paper not only the other sheet of paper must be stopped but also the feeding of further sheets of paper must be interrupted. Only when the two sheets of paper, which are in the assembly station, have been completely superposed, they can be discharged from the assembly station by means of further continuous conveyor belts arranged in the direction of movement of the paper. The vacuum conveyance unit is in a modification of this conventional device arranged symmetrically in the center between both sheets of paper, and the conveyor belt can be driven selectively in the one or other direction. It is possible in this manner to place selectively sheets of paper originating from the first row of sheets of paper above sheets of paper of the second row of sheets of paper and vice versa. However, this conventional device operates surely discontinuously cyclically, namely the feeding of sheets of paper and the discharge of sheets of paper must be interrupted in each case during the time which is needed for the transverse movement of each sheet of paper in the assembly station. This results in a relatively long cycle time and accordingly in a low performance. Also the cyclical operation of the device causes greater noises. Furthermore several stop bars are needed in the assembly station in order to assure the exact alignment of the sheet of paper to be moved transversely. These stops must be newly adjusted for each format change. Furthermore the conventional device permits always only the movement of one sheet of paper toward one or toward the other side of the device, namely a superposing with a fixed edge on the right or on the left. A center-symmetrical superposing of sheets of paper is not possible. The conventional device can also not be used universally for other methods of operation.
Therefore the basic purpose of the invention is to provide a device for superposing of sheets of paper or the like of the abovementioned type, which is distinguished in particular by a high performance, thereby operating precisely and safely, which demands little conversion operations during format change and can be adjusted universally for several different methods of operation.
This is attained according to the invention:
by at least one similar upper vacuum conveyance unit arranged above the paper path being associated with the other row of sheets of paper, of which upper vacuum conveyance unit the lower operating strand of the conveyor belt borders the paper path, and the vacuum chamber of which is open toward the lower operating strand,
by the two ends of each carrier, which ends carry each one of the guide rollers of the associated conveyor belt, being arranged one behind the other in direction of movement of the paper, and being able to be adjusted independently from one another transversely with respect to the direction of movement of the paper each by means of an adjusting device,
by a separating plate extending in the paper path being provided in the assembly station between the lower and the upper vacuum conveyance unit, and
by a guiding device being provided in the direction of movement of the paper in front of the separating plate for each row of sheets of paper, by means of which guiding device the sheets of paper originating from the one row are each fed to the operating strand of the conveyor belt of the vacuum conveyance unit associated with the row,
whereby to superpose the sheets of paper at least the carrier of one vacuum conveyance unit can be adjusted transversely with respect to the direction of movement of the paper by means of the adjusting device in such a manner that its conveyor belt crosses in the outlet-side area of the assembly station the conveyor belt of the vacuum conveyance unit arranged on the opposite side of the separating plate.
Thus the invention is based on the premise to associate each separate vacuum conveyance unit with the sheets of paper coming from each row of sheets of paper, of which vacuum conveyance units the vacuum conveyance unit associated with the one row of sheets of paper is arranged below and the other vacuum conveyance unit associated with the other row of sheets of paper is arranged above the plane of sheets of paper. The invention is furthermore based on the premise of arranging the vacuum conveyance units in such a manner that their conveyor belts extend essentially in direction of movement of the paper, and that the position of the conveyor belts relative to the direction of movement of the paper can be adjusted precisely by means of adjusting devices. In order to superpose the sheets of paper, the vacuum conveyance units can now be adjusted selectively in such a manner that, for example, the conveyor belt of the lower vacuum conveyance unit extends in direction of movement of the paper and the conveyor belt of the upper vacuum conveyance unit inclined with respect to the direction of movement of the paper. In this manner all sheets of paper are moved by the upper vacuum conveyance unit toward the side of the device where the lower vacuum conveyance unit is, and a method of operation with a fixed edge on the one side of the device is possible. When the fixed edge is to be on the other side of the device, the upper vacuum conveyance unit is adjusted in such a manner that its conveyor belt extends in direction of movement of the paper, and its lower vacuum conveyance unit so that its conveyor belt extends inclined with respect to the direction of movement of the paper. However, it is also possible to adjust the lower and the upper vacuum conveyance unit in such a manner that the conveyor belts of both vacuum conveyance units extend inclined with respect to the direction of movement of the paper toward the longitudinal center plane of the device, which causes then the sheets of paper originating from both rows of sheets of paper to be moved in the assembly station each toward the longitudinal center plane, and a center-symmetrical paper processing is possible. Further methods of operation of the new device will be discussed later on in connection with the drawings. Important for the new device is that by positioning the conveyor belt or the conveyor belts at an incline with respect to the direction of movement of the paper the superposing of the sheets of paper can occur continuously. The sheet of paper originating from one row of sheets of paper is fed continuously in direction of movement of the paper and the sheet of paper originating from the other row of sheets of paper is fed continuously inclined thereto or the sheets of paper originating from both rows of sheets of paper are fed continuously inclined with respect to the direction of movement of the paper and are thereby superposed in the assembly station depending on the adjustment of the conveyor belts. A significantly higher performance is possible with the continuous method of operation of the new device compared with conventional devices, for example the device mentioned in the beginning. Thus it is, for example, possible to process with the new device using a format height of approximately 75 mm (3 inches) 100,000 sheets per hour, whereas the present operating performance was only 25,000 sheets per hour. The new device also operates significantly quieter because of the continuous method of operation. In addition a change in format demands only few change-over operations since the edge-exact superposing of the sheets of paper can be adjusted precisely by adjusting the inclined position of the conveyor belts without the necessity of stops. Since no stops are needed, it is also possible for the sheets of paper of the one row of sheets of paper to have a different width than the ones of the other one (asymmetric longitudinal cross section).
Advantageous developments of the invention are characterized in the subclaims.